Solid-phase radioimmunoassay (RIA) of antigens or antibodies in a serum sample are well known. Catt and his co-workers have reported such techniques on the surface of plastic tubes (Science, 158: 1570 (1967); U.S. Pat. No. 3,646,346) and plastic discs (J. Lab. & Clin. Med., 70: 820 (1967). In such techniques, an excess of specific antibody is first adsorbed to a support surface. Then, the sample to be assayed is immunologically reacted with such surface in a sandwich or competitive binding technique. In the competitive binding technique, illustrated in U.S. Pat. No. 3,555,143, the concentration of antigen to be determined and a known quantity of radioactively tagged antigen are immunologically reacted with the antibody-adsorbed surface. The labelled antigen bound to the antibody on the surface is then quantitated to determine indirectly the total quantity of antigen in the original sample. It is known that such a competitive binding technique is relatively inaccurate, especially when the proportions of labeled and unlabelled antigen are diverse. In the sandwich technique, serum containing an unknown concentration of antigen is immunologically reacted with the antibody-containing surface. Then in a following step, the bound antigen is incubated with labelled antibody and the amount of immunologically bound, labelled antibody is subsequently measured. This technique includes the disadvantage of adding an additional step to the procedure.
One common disadvantage to both of the foregoing techniques is apparent when support surfaces therein used are mass produced for distribution to clinical laboratories for testing of serum or the like. An antibody specific for each antigen must be predeposited in order for the antigen concentration to be determined in the laboratory of the customer. The only alternative for the customer is to perform the preliminary antibody coating step which can be time consuming and subject to error. Another problem with shipping of such antibody coated surfaces is that they are composed of protein, which is biologically active and so susceptible to deterioration or denaturation in the presence of light, heat, alterations of pH levels, enzymes, bacteria, or other environmental conditions. This problem was recognized in U.S. Pat. No. 3,790,663 which discloses a specific preparation of a dry antiserum coated solid-phase for RIA of antigens to increase the stability of the antiserum. It is apparent that even such dry surfaces are less stable than the underlying polymeric substrate and, additionally, would require special handling to prevent removal of the antiserum as from the environment or by physical abrasion.